CN111999772A

CN111999772A - Detection device, transmitting terminal, wireless charging system and method for metal foreign matters

Info

Publication number: CN111999772A
Application number: CN201910446390.8A
Authority: CN
Inventors: 陈双全; 肖辅荣; 武志贤; 舒为亮
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-05-27
Filing date: 2019-05-27
Publication date: 2020-11-27

Abstract

The application discloses a detection device, a transmitting end, a wireless charging system and a method for a metal foreign body, wherein the input end of a first resonant circuit is connected with a constant voltage source, and the output end of the first resonant circuit is connected with a second resonant circuit; the first resonant circuit is used for converting the constant voltage source into a current source; the first resonance circuit at least comprises a series resonance circuit formed by a first inductor and a first capacitor, and the second resonance circuit at least comprises a parallel resonance circuit formed by a foreign object detection coil and a second capacitor; the resonant frequency of the first resonant circuit is consistent with the resonant frequency of the second resonant circuit; a detection circuit for detecting an electrical parameter of the first resonant circuit or the second resonant circuit; and a foreign object detection controller for comparing the detected electrical quantity with a reference value to determine whether a metallic foreign object is present. The device can reduce the influence of the induced voltage that foreign matter detection coil produced, promotes the detection device's of metallic foreign matter stability and reliability.

Description

Detection device, transmitting terminal, wireless charging system and method for metal foreign matters

Technical Field

The application relates to the technical field of wireless charging, in particular to a detection device, a transmitting terminal, a wireless charging system and a method for a metal foreign body.

Background

With the shortage of energy and the aggravation of environmental pollution in modern society, electric vehicles have received wide attention from all over as new energy vehicles. Methods of charging electric vehicles generally include: contact charging and wireless charging. The contact charging adopts the metal contact of a plug and a socket to conduct electricity, and the wireless charging realizes the transmission of electric energy by taking a coupled electromagnetic field as a medium. Compared with contact charging, wireless charging has the advantages of convenience in use, no spark, no electric shock hazard, no mechanical abrasion, adaptability to various severe environments and weathers, convenience in realizing unmanned automatic charging, movable charging and the like, and becomes the mainstream mode of charging of future electric vehicles.

In the wireless charging process, energy is transmitted between a transmitting coil of a wireless charging transmitting end and a receiving coil of a wireless charging receiving end through magnetic field coupling, when metal foreign matters exist on the transmitting coil, metal can be heated due to an eddy current effect, and potential safety hazards are easily generated; or when a screw or coin falls onto the active emitting end, may be heated to a high temperature, with the risk of scalding if someone picks up the item at that time. Therefore, in the wireless charging standards of electric vehicles in international and domestic fields, the detection of metal foreign matters is required as a safety standard.

At present, a foreign body detection coil is usually placed at a wireless charging emission end during metal foreign body detection, an excitation circuit included in a metal foreign body detection circuit applies excitation to the foreign body detection coil, and corresponding obtained responses are identified and analyzed to judge whether metal foreign bodies exist. And when wireless charging transmitting terminal during operation, can produce induced voltage on the foreign matter detection coil, this induced voltage can produce adverse effect to excitation circuit, leads to the unable normal work of metal foreign matter detection circuit even.

Disclosure of Invention

The application provides detection device, transmitting terminal, wireless charging system and detection method of metal foreign matter, when carrying out metal foreign matter and detect, has reduced the influence of the induced voltage that foreign matter detection coil produced, has promoted detection device's of metal foreign matter stability and reliability.

In a first aspect, the present application provides a device for detecting a metallic foreign object, which is applied to detecting a metallic foreign object on a power transmitting antenna; the method comprises the following steps: the detection circuit comprises a first resonance circuit, a second resonance circuit, a detection circuit and a foreign matter detection controller; the input end of the first resonant circuit is connected with a constant voltage source, and the output end of the first resonant circuit is connected with the second resonant circuit; the first resonant circuit is used for converting the constant voltage source into a current source; the first resonance circuit at least comprises a series resonance circuit formed by a first inductor and a first capacitor, and the second resonance circuit at least comprises a parallel resonance circuit formed by a foreign object detection coil and a second capacitor; the resonant frequency of the first resonant circuit is consistent with the resonant frequency of the second resonant circuit;

a detection circuit for detecting an electrical parameter of the first resonant circuit or the second resonant circuit;

and the foreign matter detection controller is used for comparing the detected electric parameter with a reference value, and determining that metal foreign matter exists when the absolute value of the difference value between the electric parameter and the reference value exceeds a preset range.

The device does not use active devices, but passive devices such as capacitors and inductors are used, and stable working voltage does not need to be provided for the passive devices, so that when the metal foreign object is detected, the detection device is little influenced by induction voltage generated on the foreign object detection coil, and the stability and reliability of the detection device for the metal foreign object are improved.

With reference to the first aspect, in a first possible implementation manner, a first end of the first inductor is connected to a first end of the constant voltage source, a second end of the first inductor is connected to a first end of the first capacitor, and a second end of the first capacitor is connected to a second end of the constant voltage source; the second resonant circuit is connected in parallel between the first terminal of the first capacitor and the second terminal of the first capacitor.

The amplitude of the resonant voltage of the series resonance formed by the first inductor and the first capacitor can be set by pre-selecting the parameter values of the first inductor and the first capacitor, so that the excitation current provided by the first resonant circuit to the second resonant circuit is determined.

With reference to the first aspect and any one of the foregoing possible implementation manners, in a second possible implementation manner, the first resonant circuit further includes: a third capacitor; the first end of the first inductor is connected with the first end of the constant voltage source, the second end of the first inductor is connected with the first end of the third capacitor, the first end of the third capacitor is connected with the first end of the first capacitor, and the second end of the first capacitor is connected with the second end of the constant voltage source; the second resonant circuit is connected in parallel between the first terminal of the first capacitor and the second terminal of said first capacitor.

The third capacitor can filter out direct current components in the circuit, and the size of exciting current provided for the second resonant circuit can be adjusted by adding the third capacitor, so that different actual configuration requirements can be met.

With reference to the first aspect and any one of the foregoing possible implementation manners, in a third possible implementation manner, the foreign object detection coil and the second capacitor are connected in parallel and then connected between the first end of the first capacitor and the second end of the first capacitor. The first resonant circuit is capable of supplying a stable excitation current to the second resonant circuit.

With reference to the first aspect and any one of the foregoing possible implementation manners, in a fourth possible implementation manner, the second resonant circuit further includes: a fourth capacitor; the foreign body detection coil is connected in series with the fourth capacitor and then connected in parallel with the second capacitor, and is connected between the first end of the first capacitor and the second end of the first capacitor after being connected in parallel.

The reactance of the second resonant circuit can be adjusted by adding the fourth capacitor to meet different practical configuration requirements.

With reference to the first aspect and any one of the foregoing possible implementation manners, in a fifth possible implementation manner, the detection circuit includes a first current sensor; a first current sensor for detecting a current flowing through the first resonance circuit; and the foreign matter detection controller is specifically used for comparing the detected current flowing through the first resonant circuit with a current reference value, and determining that the metal foreign matter exists when the absolute value of the difference value between the current flowing through the first resonant circuit and the current reference value exceeds a preset current range.

Since the current flowing through the first resonant circuit is related to the reactance of the second resonant circuit, when the reactance of the second resonant circuit is changed due to a metal foreign object, the current flowing through the first resonant circuit is also changed correspondingly, and therefore the current is detected by the first current sensor and then compared with the current reference value, and the metal foreign object on the power transmitting antenna can be determined.

With reference to the first aspect and any one of the foregoing possible implementation manners, in a sixth possible implementation manner, the detection circuit includes a voltage sensor; a voltage sensor for detecting a voltage across the second resonant circuit; and the foreign matter detection controller is specifically used for comparing the detected voltage at two ends of the second resonant circuit with a voltage reference value, and determining that the metal foreign matter exists when the absolute value of the difference value between the voltage at two ends of the second resonant circuit and the voltage reference value exceeds a preset voltage range.

Since the voltage across the second resonant circuit is related to the reactance of the second resonant circuit, when the reactance of the second resonant circuit changes due to a metal foreign object, the voltage across the second resonant circuit also changes accordingly, and therefore the voltage is detected by the voltage sensor and then compared with a voltage reference value to determine whether the metal foreign object exists on the power transmitting antenna.

With reference to the first aspect and any one of the foregoing possible implementation manners, in a seventh possible implementation manner, the detection circuit includes a voltage sensor and a second current sensor; a voltage sensor for detecting a voltage across the second resonant circuit; a second current sensor for detecting a current flowing through the second resonance circuit; a foreign object detection controller for obtaining a reactance of the second resonance circuit based on a voltage across the second resonance circuit and a current flowing through the second resonance circuit; and comparing the reactance of the second resonance circuit with a reactance reference value, and determining that the metal foreign matter exists when the absolute value of the difference value between the reactance of the second resonance circuit and the reactance reference value exceeds a preset reactance range.

Since the metal foreign matter may cause a change in the reactance of the second resonant circuit, the reactance of the second resonant circuit may be obtained by detecting the voltage across the second resonant circuit and the current flowing through the second resonant circuit, and then compared with a reactance reference value to determine whether the metal foreign matter is present on the power transmitting antenna.

In a second aspect, the present application provides a transmitting terminal, which comprises any one of the above-described detecting devices for metal foreign matters; further comprising: a power transmitting antenna; a power transmitting antenna for transmitting the alternating magnetic field; and the detection device of the metal foreign matter is used for detecting whether the metal foreign matter exists on the power transmitting antenna.

Because the transmitting terminal comprises the detection device for the metal foreign matters, the metal foreign matters existing on the power transmitting antenna of the transmitting terminal can be found in time during working, the influence of induction voltage generated on the foreign matter detection coil is reduced, and potential safety hazards are eliminated.

With reference to the second aspect, in a first possible implementation manner, the transmitting end further includes: a transmitting end controller; the transmitting terminal controller is used for receiving the foreign matter detection result sent by the foreign matter detection controller; and is also used for sending a foreign matter detection starting instruction and a foreign matter detection stopping instruction to the foreign matter detection controller.

The transmitting end controller can control the starting and stopping of the foreign matter detection, and can also perform corresponding control operation according to other working state information fed back by the foreign matter detection controller, such as current temperature information, fault information of the detection device and the like.

In a third aspect, the present application provides a wireless charging system, which includes any one of the above transmitting terminals, and further includes a receiving terminal; the transmitting terminal is used for transmitting the alternating current in the form of an alternating magnetic field; and the receiving end is used for receiving the alternating current in the form of the alternating magnetic field transmitted by the transmitting end and providing the alternating current to the power utilization terminal.

Because this wireless charging system includes the detection device of the metallic foreign matter of above introduction, consequently can in time discover the metallic foreign matter that exists on the power transmitting antenna of transmitting terminal at the during operation, reduced and received the influence of the induced voltage that produces on the foreign matter detection coil, get rid of the potential safety hazard.

In a fourth aspect, the present application provides a method for detecting a metallic foreign object, which is applied to detecting a metallic foreign object on a power transmitting antenna; the detection method is carried out by using a detection device, and the detection device at least comprises the following steps: a first resonant circuit, a second resonant circuit; the input end of the first resonant circuit is connected with a constant voltage source, and the output end of the first resonant circuit is connected with the second resonant circuit; the first resonant circuit is used for converting a constant voltage source into a current source, and the voltage of the constant voltage source is the product of the total reactance of the first resonant circuit and the second resonant circuit and the current of the current source; the first resonance circuit at least comprises a series resonance circuit formed by a first inductor and a first capacitor, and the second resonance circuit at least comprises a parallel resonance circuit formed by a foreign object detection coil and a second capacitor; the resonant frequency of the first resonant circuit is consistent with the resonant frequency of the second resonant circuit; the foreign body detection coil is close to the power transmitting antenna; the method comprises the following steps: detecting an electrical parameter of the first resonant circuit or the second resonant circuit;

and comparing the detected electric parameter with a reference value, and determining that the metal foreign matter exists when the absolute value of the difference value between the electric parameter and the reference value exceeds a preset range.

Due to the adoption of the method, the metal foreign matters existing on the power transmitting antenna of the transmitting end can be found in time when the power transmitting antenna works, and potential safety hazards are eliminated.

According to the technical scheme, the embodiment of the application has at least the following advantages:

the first resonant circuit that includes in the detection device of metallic foreign object that this application embodiment provided can convert the constant voltage source into stable current source, with the excitation as second resonant circuit, active device is not used in this first resonant circuit, but passive devices such as electric capacity and inductance have been used, the simple structure of circuit, the circuit cost is reduced, need not provide stable operating voltage for foretell passive device simultaneously, when carrying out metallic foreign object detection, the influence of the induced voltage who produces on the foreign object detection coil has been reduced, metallic foreign object's detection device's stability and reliability have been promoted. When a metal foreign body exists on the foreign body detection coil, the inductance of the foreign body detection coil can be changed by the eddy current effect of the metal foreign body, and then the electric parameters of the first resonance circuit and the second resonance circuit are changed. The detection circuit can detect the electric parameter of the first resonance circuit or the second resonance circuit, the foreign matter detection controller compares the detected electric parameter with a reference value, and when the absolute value of the difference value of the electric parameter and the reference value exceeds a preset range, the metal foreign matter on the power transmitting antenna can be determined.

Drawings

Fig. 1 is a schematic diagram of an electric vehicle wireless charging system provided in the present application;

fig. 2 is a schematic position diagram of a foreign object detection coil and a power transmitting antenna provided in the present application;

fig. 3 is a schematic view of a device for detecting metal foreign matter according to an embodiment of the present disclosure;

fig. 4 is a schematic view of another device for detecting metal foreign matter according to the second embodiment of the present application;

fig. 5 is a schematic view of another device for detecting metal foreign matter according to the second embodiment of the present application;

fig. 6 is a schematic view of another apparatus for detecting metal foreign matter according to the second embodiment of the present application;

fig. 7 is a schematic view of another device for detecting metal foreign matter according to the third embodiment of the present application;

fig. 8 is a schematic view of another device for detecting metal foreign matter according to the third embodiment of the present application;

fig. 9 is a schematic view of another device for detecting metal foreign matter according to the third embodiment of the present application;

fig. 10 is a schematic view of another metal foreign object detection apparatus provided in the third embodiment of the present application;

fig. 11 is a schematic diagram of a transmitting end according to a fourth embodiment of the present application;

fig. 12 is a schematic diagram of another transmitting end according to the fourth embodiment of the present application;

fig. 13 is a schematic view of a wireless charging system according to a fifth embodiment of the present application;

fig. 14 is a flowchart of a method for detecting a metal foreign object according to a sixth embodiment of the present application.

Detailed Description

In order to make those skilled in the art better understand the technical solution provided by the embodiments of the present application, an application scenario of the detection apparatus for metal foreign matter is first described below. The detection device for the metal foreign matters is applied to metal foreign matter detection on a power transmitting antenna, namely whether the metal foreign matters exist on the power transmitting antenna is detected, the detection device can be arranged at a transmitting end of a wireless charging system and can also be arranged at a receiving end of the wireless charging system, and the detection device is suitable for various scenes using the power transmitting antenna, for example, the transmitting end in the wireless charging system has the power transmitting antenna, a typical scene applied by the wireless charging system is used for wirelessly charging an electric automobile, and the following description is given by taking an application scene applied to the wireless charging system for charging the electric automobile as an example in combination with the accompanying drawings. Of course, the device for detecting a metal foreign object may also be applied to other application scenarios, for example, a scenario without a power transmitting antenna to detect a metal foreign object, which is not specifically limited in the embodiment of the present application. Referring to fig. 1, the figure is a schematic diagram of an electric vehicle wireless charging system provided in the present application.

The wireless charging system at least includes: electric vehicle 100 and wireless charging station 200.

The electric vehicle 100 includes a wireless charging receiving terminal 101, and the wireless charging station 200 includes a wireless charging transmitting terminal 201.

Currently, the charging process of the wireless charging system is to perform contactless charging by the wireless charging receiving terminal 101 located in the electric vehicle 100 and the wireless charging transmitting terminal 201 located in the wireless charging station 200 working together.

The wireless charging station 200 may be a fixed wireless charging station, a fixed wireless charging parking space, a wireless charging road, or the like. The wireless charging transmitting terminal 201 may be disposed on the ground or buried under the ground (fig. 1 shows a case where the wireless charging transmitting terminal 201 is buried under the ground), and may wirelessly charge the electric vehicle 100 located above the wireless charging transmitting terminal.

The wireless charging receiving terminal 101 may be integrated at the bottom of the electric vehicle 100, and when the electric vehicle 100 enters the wireless charging range of the wireless charging transmitting terminal 201, the electric vehicle 100 may be charged in a wireless charging manner. The power receiving antenna and the rectifying circuit of the wireless charging receiving terminal 101 may be integrated together or separated, and the rectifier in the rectifying circuit is usually placed in the vehicle during separation.

The power transmitting antenna and the inverter of the wireless charging transmitting terminal 201 may be integrated together or separated. In addition, the non-contact charging may be that the wireless charging receiving terminal 101 and the wireless charging transmitting terminal 201 perform wireless energy transmission in an electric field or magnetic field coupling manner, specifically, may be in an electric field induction, magnetic resonance, or wireless radiation manner, which is not limited in this embodiment of the application. Further, the electric vehicle 100 and the wireless charging station 200 can be charged in both directions, that is, the wireless charging station 200 charges the electric vehicle 100 by the power supply, and the electric vehicle 100 can also discharge the power supply.

The detection device for the metal foreign matter may be disposed at the wireless charging transmitting terminal 201, or may be disposed at the electric vehicle 100. The following description will take an example in which the detection device for the metallic foreign object is installed in the wireless charging transmitter 201. Referring to fig. 2, the position of the foreign object detection coil and the power transmitting antenna provided by the present application is schematically shown.

When metal foreign body detection is carried out, a foreign body detection coil is usually placed at an emission end, excitation is applied to the foreign body detection coil, and the obtained corresponding response is identified and analyzed to judge whether metal foreign bodies exist. As shown in fig. 2, the power transmitting antenna 203 is located at the wireless charging transmitting end, the foreign object detection coil 202 is located near the upper side of the power transmitting antenna 203, the foreign object detection coil of the detection device may be an array formed by a plurality of coils, and in order to ensure that whether a metal foreign object exists on the power transmitting antenna 203 can be detected comprehensively, the foreign object detection coil 202 may cover the power transmitting antenna 203, and the shape and the arrangement rule of the foreign object detection coil 202 are not specifically limited in the present application.

Because an excitation circuit needs to be built for applying excitation to the foreign object detection coil, when the excitation is a constant current source, an operational amplifier is usually used for building the excitation circuit, the operational amplifier is an active device, stable working voltage needs to be provided for the operational amplifier, the working voltage of the operational amplifier is limited, when the emission end works, an induced voltage can be generated on the foreign object detection coil, the magnitude of the induced voltage can reach dozens of volts or even hundreds of volts, and when the induced voltage exceeds the working voltage of the operational amplifier, the operational amplifier can be influenced or even damaged, and the metal foreign object detection circuit can not work normally.

In order to solve the above technical problem, an embodiment of the present application provides a detection apparatus for a metal foreign object, where a first resonant circuit of the detection apparatus can convert a constant voltage source into a stable current source to be used as excitation of a second resonant circuit, and a passive device such as a capacitor and an inductor is used instead of an active device in the first resonant circuit.

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

The first embodiment is as follows:

referring to fig. 3, the figure is a schematic view of a device for detecting a metal foreign object according to an embodiment of the present application.

The detection device for the metal foreign matter can be applied to various scenes using the power transmitting antenna, for example, the power transmitting antenna of the transmitting end in the wireless charging system can be specifically arranged at the transmitting end of the wireless charging system, and can also be arranged at the receiving end of the wireless charging system, namely, the detection device for the metal foreign matter on the receiving end detects whether the metal foreign matter exists on the power transmitting antenna of the transmitting end. The metallic foreign matter detection apparatus 300 includes: a first resonance circuit 301, a second resonance circuit 302, a detection circuit 303, and a foreign object detection controller 304.

The input end of the first resonant circuit 301 is connected to a constant voltage source 305, the constant voltage source 305 may be implemented by a circuit with a half-bridge or full-bridge structure, and the constant voltage source 305 may be powered by an external power source or a power source located inside the transmitting end, which is not specifically limited in this embodiment of the present application. The output of the first resonance circuit 301 is connected to the second resonance circuit 302.

The first resonant circuit 301 comprises at least a series resonant circuit formed by a first inductance and a first capacitance.

The first resonant circuit 301 is configured to convert a constant voltage source into a current source and provide an excitation to the second resonant circuit 302, and the magnitude of the resonant voltage of the first resonant circuit can be autonomously designed by pre-selecting the parameter values of the first inductor and the first capacitor included in the first resonant circuit, so as to determine the excitation current provided by the first resonant circuit 301 to the second resonant circuit 302.

The second resonance circuit 302 includes at least a parallel resonance circuit formed by the foreign object detection coil and the second capacitor.

The resonance frequency of the first resonance circuit 301 coincides with the resonance frequency of the second resonance circuit 302.

The dashed line in fig. 3 indicates that the detection circuit 303 can detect the electrical quantity of the first resonance circuit 301 or the second resonance circuit 302. The electrical quantities may include current, voltage, reactance, and the like, and when the electrical quantities are current and voltage, the measured current and voltage are vectors including magnitude and phase.

The foreign object detection controller 304 can compare the electric parameter detected by the detection circuit 303 with a corresponding reference value, and determine that a metallic foreign object exists when the absolute value of the difference between the electric parameter and the reference value exceeds a preset range. This is because when a metal foreign object exists on the power transmitting antenna, the eddy current effect of the metal foreign object causes the inductance of the foreign object detection coil of the second resonant circuit 302 to change, thereby causing the electrical parameters of the first resonant circuit 301 and the second resonant circuit 302 to change.

The preset range may be set according to actual requirements, and the embodiment of the present application is not particularly limited, for example, the preset range may be set to be 1% of the reference value, when an absolute value of a difference between the detected electrical parameter and the reference value is less than or equal to 1% of the reference value, the difference may be considered as a detection error, and when the absolute value is greater than 1% of the reference value, it is determined that a metal foreign object exists.

The foreign object detection controller 304 may also perform information interaction with a transmitting terminal controller of the wireless charging system, send a foreign object detection result to the transmitting terminal controller in real time or at regular time, and feed back status information such as temperature information and fault information of the detection device for the metal foreign object to the transmitting terminal controller.

It is understood that the detection circuit 303 may also detect the electrical parameters of the first resonance circuit 301 and the second resonance circuit 302 at the same time, and the foreign object detection controller 304 may compare the electrical parameters detected by the detection circuit 303 with corresponding reference values, respectively, so as to obtain a plurality of detection results, which may be compared and verified with each other.

In addition, the detection device for the metal foreign bodies can also be applied to other metal detection fields, such as security metal detection and the like.

The detection device of metallic foreign object that this application embodiment provided's first resonant circuit is used for converting the constant voltage source into stable current source and provides the second resonant circuit, do not use active device among this first resonant circuit, but passive devices such as electric capacity and inductance have been used, owing to need not provide stable operating voltage for above-mentioned passive device, consequently when carrying out metallic foreign object detection, the detection device that this application embodiment provided has reduced the influence that receives the induced voltage that produces on the foreign object detection coil, metallic foreign object's detection device's stability and reliability have been promoted. The excitation current provided to the second resonant circuit can also be determined by pre-selecting the parameter values of the inductance and capacitance comprised in the first resonant circuit to meet different practical configuration requirements. The detection circuit of the device can detect the electric parameter of the first resonance circuit or the second resonance circuit, the inductance of the foreign matter detection coil can be changed due to the eddy current effect of the metal foreign matter, the electric parameter of the first resonance circuit and the electric parameter of the second resonance circuit can be further changed, the foreign matter detection controller compares the detected electric parameter with a reference value, and when the absolute value of the difference value of the electric parameter and the reference value exceeds a preset range, the metal foreign matter on the power emission antenna can be determined.

The detection circuit included in the device can detect the electric parameters of the first resonance circuit or the second resonance circuit, and the foreign object detection controller compares different electric parameters detected by the detection circuit with corresponding reference values.

Example two:

referring to fig. 4, the figure is a schematic view of another detection apparatus for metal foreign matter according to the second embodiment of the present application.

The first resonance circuit 401 of the arrangement comprises: a first inductor L1 and a first capacitor C1.

A first terminal of the first inductor L1 is connected to a first terminal of the constant voltage source 305, a second terminal of the first inductor L1 is connected to a first terminal of the first capacitor C1, and a second terminal of the first capacitor C1 is connected to a second terminal of the constant voltage source 305. The second resonant circuit 302 is connected in parallel between the first terminal of the first capacitor C1 and the second terminal of the first capacitor C1. For the description of other parts included in the apparatus, reference may be made to embodiment one, and details are not described herein.

The magnitude of the resonant voltage of the series resonance formed by the first inductor L1 and the first capacitor C1 can be designed autonomously by pre-selecting the values of the parameters of the first inductor L1 and the first capacitor C1, thereby determining the excitation current provided by the first resonant circuit 401 to the second resonant circuit 302.

Referring to fig. 5, this figure is a schematic view of another detection apparatus for metal foreign matter according to the second embodiment of the present application.

The apparatus differs from the apparatus provided in fig. 4 in that the first resonant circuit 501 further comprises: a third capacitor C3.

A first terminal of the first inductor L1 is connected to a first terminal of the constant voltage source 305, a second terminal of the first inductor L1 is connected to a first terminal of a third capacitor C3, a second terminal of the third capacitor C3 is connected to a first terminal of a first capacitor C1, and a second terminal of the first capacitor C1 is connected to a second terminal of the constant voltage source 305. The second resonant circuit 305 is connected in parallel between a first terminal of the first capacitor C1 and a second terminal of the first capacitor C1. For the description of other parts included in the apparatus, reference may be made to embodiment one, and details are not described herein.

The third capacitor C3 can filter out the dc component in the circuit. The addition of the third capacitor C3 to the circuit of fig. 4 also enables the magnitude of the excitation current supplied to the second resonant circuit 302 to be adjusted to meet different practical configuration requirements.

Referring to fig. 6, it is a schematic view of another apparatus for detecting metal foreign matter according to the second embodiment of the present application.

The apparatus differs from the apparatus shown in fig. 4 in that: the detection circuitry in the apparatus of fig. 6 comprises a first current sensor 603. The first current sensor 603 is used to detect the current flowing through the first resonant circuit 401, and the electrical quantity detected by the detection circuit is the current flowing through the first resonant circuit 401, which is denoted by iL in the figure.

The detection principle of the device is specifically described below by taking the device shown in fig. 6 as an example, and it can be understood that the detection principle is similar when the third capacitor is further included in the first resonant circuit of the device, and the description is not repeated here.

The constant voltage source 305 outputs an ac voltage of a predetermined frequency, hereinafter denoted by Uin, and a frequency of the ac voltage denoted by ω, to the first resonant circuit 501.

When no metallic foreign object is present on the power transmitting antenna, the resonance frequency of the second resonance circuit 302 coincides with the resonance frequency of the first resonance circuit 401, also ω. By Z representing the reactance of the second resonant circuit 302, the current iL through the first resonant circuit 401 can be obtained by the following equation:

when Uin of the constant voltage source output is constant, the frequency ω of Uin is constant, and the first inductance L1 and the first capacitance C1 are fixed in equation (1), the current iL flowing through the first resonant circuit 401 is related to the reactance Z of the second resonant circuit.

Therefore, the current flowing through the first resonance circuit 401 when no metallic foreign object is present on the power transmitting antenna can be determined from the known Uin, ω, the inductance value of the first inductance L1, the capacitance value of the first capacitance C1, and the reactance Z of the second resonance circuit 302, and the current value is set as a current reference value.

When a metal foreign object exists on the power transmitting antenna, the inductance of the foreign object detection coil of the second resonant circuit 302 changes due to the eddy current effect, which causes the reactance Z of the second resonant circuit 302 to change, and further causes the current iL flowing through the first resonant circuit 401 to change.

The first current sensor 603 detects the current iL currently flowing through the first resonance circuit 401. The foreign object detection controller 304 then compares the detected current iL with a current reference value, and determines that a metallic foreign object is present when the absolute value of the difference between the current iL and the current reference value exceeds a preset current range.

The preset current range may be set according to actual conditions, for example, the preset current range may be set to be 3% to 5% of the current reference value, which is exemplified below:

the preset current range is set to be 5% of the current reference value, when the absolute value of the difference between the current iL and the current reference value is less than or equal to 5% of the current reference value, the difference can be regarded as a measurement error, otherwise, the existence of the metal foreign matter is determined, for example, when the current reference value is 500mA and the absolute value of the difference between the current iL and the current reference value is greater than 25mA, the existence of the metal foreign matter is determined.

The detection device of metallic foreign matter that this application embodiment provided includes first resonant circuit can convert the constant voltage source into stable current source, with the excitation as second resonant circuit, active device is not used in this first resonant circuit, but passive devices such as electric capacity and inductance have been used, the simple structure of circuit, circuit cost is reduced, simultaneously because need not provide stable operating voltage for above-mentioned passive device, consequently when carrying out metallic foreign matter detection, the influence that receives the induced voltage that produces on the foreign matter detection coil has been reduced, metallic foreign matter's detection device's stability and reliability have been promoted. In addition, when the detection circuit includes the first current sensor, it is possible to detect a current flowing through the first resonance circuit, since the current is related to the reactance of the second resonance circuit, and when a metallic foreign object causes a change in the reactance of the second resonance circuit, the current flowing through the first resonance circuit is also changed accordingly, and the foreign object detection controller can determine that the metallic foreign object is present on the power transmission antenna by comparing the detected current with a current reference value, and when an absolute value of a difference between the current and the current reference value exceeds a preset range.

The following describes an implementation of the second resonant circuit and an operation principle of the device for detecting a metallic foreign object when the detection circuit detects an electrical parameter of the second resonant circuit with reference to the drawings. In the following embodiments, the first resonant circuit including the first inductor and the first capacitor is taken as an example for description, and the principle when the first resonant circuit includes the third capacitor is similar, and the description is not repeated.

Example three:

referring to fig. 7, it is a schematic view of another detection apparatus for metal foreign matter provided in the third embodiment of the present application.

The second resonance circuit 402 of the apparatus comprises: a foreign object detection coil L2, and a second capacitance C2.

The foreign object detection coil L2 and the second capacitor C2 are connected in parallel and then connected between the first terminal of the first capacitor C1 and the second terminal of the first capacitor C1. For the description of other parts included in the device, reference may be made to the first embodiment and the second embodiment, which are not described herein again.

Referring to fig. 8, this figure is a schematic view of another detection apparatus for metal foreign matter according to the third embodiment of the present application.

The apparatus differs from the apparatus provided in fig. 7 in that the second resonant circuit 602 further comprises: a fourth capacitor C4.

The foreign object detection coil L2 is connected in series with the fourth capacitor C4, connected in parallel with the second capacitor, and connected in parallel between the two ends of the first capacitor C1.

The arrangement is able to meet different practical configuration requirements by adding a fourth capacitor C4 to adjust the reactance of the second resonant circuit 302.

Referring to fig. 9, it is a schematic view of another detection apparatus for metal foreign matter according to the third embodiment of the present application.

This device differs from the device shown in fig. 7 in that: the detection circuit in the apparatus shown in fig. 9 includes a voltage sensor 703. The voltage sensor 703 is used to detect the voltage across the second resonant circuit 402, i.e. the electrical quantity detected by the detection circuit at this time is the voltage across the second resonant circuit 402, which is denoted by Up in the figure.

First, the detection principle of the apparatus is specifically described by taking the apparatus shown in fig. 9 as an example, and it is understood that the detection principle is similar when the second resonant circuit of the apparatus adopts the structure shown in fig. 8, and the description is not repeated here.

For a first resonant circuit comprising a first inductance L1 and a first capacitance C1, the following relationship exists:

the resonant frequency of the first resonant circuit 401 coincides with the resonant frequency of the second resonant circuit 402, continuing to denote the reactance of the second resonant circuit 402 by Z and the current through the second resonant circuit 402 by ip, which can be obtained by the following equation:

combining equation (2) with equation (3) yields the following equation:

when Uin outputted by the constant voltage source is constant, the frequency ω of Uin is constant, and the first inductor L1 is fixed in equation (4), the current ip flowing through the second resonant circuit 402 is a constant current, and the voltages Up and ip at two ends of the second resonant circuit 402 have the following relationship:

U_p＝i_p×Z(5)

combining equation (4) with equation (5) yields the following equation:

in equation (6), the voltage UP across the second resonant circuit 402 is proportional to the reactance Z.

Therefore, the voltage across the second resonant circuit 402 when no metallic foreign object is present on the power transmitting antenna can be determined from the known Uin, the frequency ω, and the inductance of the first inductance, and the voltage across the second resonant circuit 402 at this time is set as the voltage reference value.

When a metal foreign object exists on the power transmitting antenna, the inductance of the foreign object detection coil of the second resonant circuit 402 is changed due to the eddy current effect of the metal foreign object, so that the reactance Z of the second resonant circuit 402 is changed, and further, the voltage UP at two ends of the second resonant circuit 402 is changed.

The voltage sensor 703 detects the present voltage UP across the second resonant circuit 402. The foreign object detection controller 304 then compares the detected voltage UP with a voltage reference value, and determines that a metallic foreign object exists when the absolute value of the difference between the voltage UP and the voltage reference value exceeds a preset voltage range.

The preset voltage range may be set according to actual conditions, for example, the preset voltage range may be set to be 3% to 5% of the voltage reference value, when an absolute value of a difference between the voltage UP and the voltage reference value is less than or equal to 3% to 5% of the voltage reference value, the difference may be considered as a measurement error, otherwise, it is determined that a metal foreign object exists.

Referring to fig. 10, the figure is a schematic view of another detection apparatus for metal foreign matter provided in the third embodiment of the present application.

The device differs from fig. 9 in that: the detection circuit of the apparatus shown in fig. 10 includes a voltage sensor 703 and a second current sensor 704.

The voltage sensor 703 is configured to detect a voltage UP across the second resonant circuit, the second current sensor 704 is configured to detect a current ip flowing through the second resonant circuit, the detected voltage UP and the detected current ip are vectors, that is, the detection result includes the amplitude and the phase of the electrical parameter, and then the following relationship exists between the voltage UP, the current ip, and the reactance Z of the second resonant circuit 402:

when no metallic foreign object is present on the power transmitting antenna, the reactance of the second resonance circuit 402 is set to the reactance reference value.

When a metal foreign object exists on the power transmitting antenna, the inductance of the foreign object detection coil of the second resonant circuit 402 is changed due to the eddy current effect of the metal foreign object, and then the reactance Z of the second resonant circuit 402 is changed.

At this time, the foreign object detection controller 304 obtains the reactance of the second resonance circuit based on the measured voltage UP across the second resonance circuit and the current ip flowing through the second resonance circuit, compares the reactance of the second resonance circuit with the reactance reference value, and determines that there is a metallic foreign object when the absolute value of the difference between the reactance of the second resonance circuit and the reactance reference value exceeds the preset reactance range.

The preset reactance range may be set according to actual conditions, for example, the preset reactance range may be set to be 3% to 5% of the reactance reference value, when an absolute value of a difference between the reactance of the second resonant circuit and the reactance reference value is less than or equal to 3% to 5% of the reactance reference value, the difference may be considered as a measurement error, otherwise, it is determined that a metal foreign object exists.

The detection device of metallic foreign matter that this application embodiment provided includes first resonant circuit can convert the constant voltage source into stable current source, with the excitation as second resonant circuit, active device is not used in this first resonant circuit, but passive devices such as electric capacity and inductance have been used, the simple structure of circuit, circuit cost is reduced, simultaneously because need not provide stable operating voltage for above-mentioned passive device, consequently when carrying out metallic foreign matter detection, the influence that receives the induced voltage that produces on the foreign matter detection coil has been reduced, metallic foreign matter's detection device's stability and reliability have been promoted. The eddy current effect of the metal foreign matter can cause the electric parameter of the second resonant circuit to change, so that the electric parameter of the second resonant circuit is detected through the detection circuit, namely, the voltage at two ends of the second resonant circuit or the reactance of the second resonant circuit is detected, then the foreign matter detection controller compares the detected electric parameter with a reference value, and when the absolute value of the difference value of the electric parameter and the reference value exceeds a preset range, the metal foreign matter on the power transmitting antenna can be determined.

Example four:

based on the detection device for the metal foreign matter provided by the above embodiment, a fourth embodiment of the present application further provides an emission end, which is specifically described below with reference to the accompanying drawings.

Referring to fig. 11, the figure is a schematic diagram of a transmitting end according to a fourth embodiment of the present application.

This transmitting terminal 800 can be applied to the transmitting terminal in scenes such as parking area, parking stall and charging station platform, and transmitting terminal 800 includes: a detection device 300 for metal foreign matter and a power transmitting antenna 801.

The power transmitting antenna 801 is used to transmit an alternating magnetic field.

The metal foreign object detection device 300 is used for detecting whether metal foreign objects exist on the power transmitting antenna 801. The working principle of the device 300 for detecting metal foreign matters can be referred to the above embodiments, and will not be described herein.

The foreign object detection coil included in the device 300 for detecting metallic foreign objects is generally located above the power transmitting antenna 801 to detect whether metallic foreign objects exist above the inductive power transmitting antenna, and is not directly connected to the power transmitting antenna 801.

The transmitting terminal 800 may further include a constant voltage source 305, where the constant voltage source 305 is configured to provide an ac voltage with a predetermined frequency to the detection apparatus 300 for metal foreign objects, and the constant voltage source 305 may be implemented by a half-bridge circuit, a full-bridge circuit, or the like.

Referring to fig. 12, the figure is a schematic diagram of another transmitting end provided in the fourth embodiment of the present application.

The transmitting terminal 900 further includes: the transmitting end controller 901.

The transmitting-side controller 901 can receive the foreign object detection result transmitted from the foreign object detection controller 304, and can also transmit a foreign object detection start instruction and a foreign object detection stop instruction to the foreign object detection controller 304.

In addition, the foreign object detection controller 304 may also feed back other operation state information of the detection apparatus 300, such as current temperature information, fault information of the detection apparatus, and the like, to the transmitting-end controller 901. The transmitting-end controller 901 may perform corresponding control operations according to the received information.

The transmitting terminal that this application embodiment provided has included the detection device of metallic foreign object, the first resonant circuit that includes in this detection device can convert the constant voltage source into stable current source, with the excitation as second resonant circuit, active device is not used in this first resonant circuit, but passive devices such as electric capacity and inductance have been used, the simple structure of circuit, the circuit cost is reduced, simultaneously because need not provide stable operating voltage for above-mentioned passive device, consequently when carrying out metallic foreign object detection, the influence that receives the induced voltage that produces on the foreign object detection coil has been reduced, metallic foreign object's detection device's stability and reliability have been promoted. Therefore, when the wireless charging system works, the metal foreign matters existing on the power transmitting antenna of the transmitting terminal can be found in time, and potential safety hazards are eliminated.

Example five:

based on the transmitting terminal provided by the above embodiment, a fifth embodiment of the present application further provides a wireless charging system, which is specifically described below with reference to the accompanying drawings.

Referring to fig. 13, this figure is a schematic view of a wireless charging system according to a fifth embodiment of the present application.

This wireless charging system includes: a transmitting end 1201 and a receiving end 1101.

The transmitting end 1201 can transmit alternating current in the form of an alternating magnetic field, and the receiving end 1101 can receive the alternating current in the form of the alternating magnetic field transmitted by the transmitting end 1201 and provide the alternating current to the electric terminal.

The transmitting terminal 1201 can be applied to the wireless charging station 200 shown in fig. 1, and the receiving terminal 1101 can be applied to the electric vehicle 100 shown in fig. 1.

Fig. 1 is a schematic structural diagram of an electric vehicle wireless charging system.

The wireless charging system includes the detection device for the metallic foreign object provided in the above embodiment, and the detection device for the metallic foreign object may be disposed at a transmitting end or a receiving end of the wireless charging system, which is described below by taking the case of being disposed at the transmitting end as an example.

The transmitting end 1201 shown in fig. 13 includes: the system comprises a transmission conversion module 1201a1, a power transmission antenna 1201a2, a transmitting terminal controller 1201a3, a communication module 1201a4, an authentication management module 1201a5, a storage module 1201a6 and a metal foreign object detection device 1201a 7.

The receiving end 1101 includes: the power receiving antenna 1101a2, the receiving control module 1101a3, the receiving transformation module 1101a1, the vehicle communication module 1101a4, the energy storage management module 1101a5 and the energy storage module 1101a 6. In addition, the receiving conversion module 1101a1 may be connected to the energy storage module 1101a6 through the energy storage management module 1101a5, and use the received energy for charging the energy storage module 1101a6, and further for driving the electric vehicle. It should be noted that the energy storage management module 1101a5 and the energy storage module 1101a6 may be located inside the receiving end 1101, or may be located outside the receiving end 1101, which is not specifically limited in this embodiment of the present application.

The transmission converting module 1201a1 may be connected to an external power supply, and convert ac power or dc power obtained from the external power supply into high-frequency ac power, and when the input of the external power supply is ac power, the transmission converting module 1201a1 includes at least a power factor correction unit and an inverter; when the input of the external power source is dc, the transmitting transformation module 1201a1 includes at least an inverter. The power factor correction unit is used for enabling the phase of input current of the wireless charging system to be consistent with the phase of voltage of a power grid, reducing harmonic content of the wireless charging system, improving power factor values, reducing pollution of the wireless charging system to the power grid, and improving reliability. The inverter is used for converting the voltage output by the power factor correction unit into a high-frequency alternating voltage, and then the high-frequency alternating voltage acts on the power transmitting antenna 1201a2, so that the high-frequency alternating voltage can improve the transmitting efficiency and the transmission distance. Fig. 13 illustrates an example in which the transmitting terminal 1201 is externally connected to an external power source, and it is understood that the power source may also be a power source inside the transmitting terminal 1201.

The power transmitting antenna 1201a2 is used to transmit the alternating current output by the transmission transformation module 1201a1 in the form of an alternating magnetic field.

The transmitting terminal controller 1201a3 may control the voltage, current and frequency transformation parameter adjustment of the transmitting transformation module 1201a1 according to the transmitting power requirement of the actual wireless charging, so as to control the voltage and current output adjustment of the high-frequency alternating current in the power transmitting antenna 1201a 2.

The metallic foreign object detection device 1201a7 is used to detect whether a metallic foreign object is present above the power transmission antenna 1201a 2. The specific operation principle of the metal foreign object detection device 1201a7 can be referred to the above embodiments, and will not be described herein.

The communication module 1201a4 and the vehicle communication module 1101a4 are used to implement wireless communication between the transmitting end 1201 and the receiving end 1101, including power control information, fault protection information, on/off information, mutual authentication information, and the like. On one hand, the transmitting terminal 1201 can receive the attribute information, the charging request, the mutual authentication information and other information of the electric vehicle sent by the receiving terminal 1101; on the other hand, the transmitting end 1201 may also transmit wireless charging transmission control information, mutual authentication information, wireless charging history data information, and the like to the receiving end 1101. Specifically, the Wireless Communication mode may include, but is not limited to, any one or a combination of multiple types of Bluetooth (Bluetooth), Wireless-Fidelity (Wi-Fi), ZigBee (ZigBee), Radio Frequency Identification (RFID), Long Range (Lora), and Near Field Communication (NFC). Further, the communication module 1201a4 may also communicate with an intelligent terminal of an affiliated user of the electric vehicle, and the affiliated user realizes remote authentication and user information transmission through a communication function.

The authentication management module 1201a5 is used for mutual authentication and authority management between the transmitting terminal 1201 and the electric vehicle in the wireless charging system.

The storage module 1201a6 is configured to store charging process data, mutual authentication data (e.g., mutual authentication information), rights management data (e.g., rights management information), and the like of the transmitting end 1201, where the mutual authentication data and the rights management data may be factory set or may be set by a user, and the embodiment of the present application is not limited to this specifically.

A power receiving antenna 1101a2 for receiving electromagnetic energy transmitted by the power transmitting antenna 1201a2 in the form of an alternating magnetic field. The compensation circuit of the power transmitting antenna 1201a2 and the power receiving antenna 1101a2 in the wireless charging system may be in the form of S-S type, P-P type, S-P type, P-S type, LCL-LCL type, LCL-P type, or the like, but the present application is not limited thereto. In addition, in order to implement the bidirectional charging function of the wireless charging system, the transmitting end 1201 and the receiving end 1101 of the wireless charging system may further include a power receiving antenna and a power transmitting antenna, which may be independent or integrated.

The receiving and converting module 1101a1 is configured to convert electromagnetic energy received by the power receiving antenna 1101a2 into a dc voltage and a dc current required for charging the energy storage module 1101a 6. The reception conversion module 1101a1 includes at least a compensation circuit and a rectifier, wherein the rectifier converts the high-frequency resonance current and voltage received by the power reception antenna into a direct-current voltage and a direct current.

The reception control module 1101a3 can control the voltage, current and frequency conversion parameter adjustments of the reception conversion module 1101a1 according to the reception power demand of the actual wireless charging.

The first resonant circuit that the transmitting terminal of the wireless charging system that this application embodiment provided includes can convert the constant voltage source into stable current source, with the excitation as second resonant circuit, active device is not used in this first resonant circuit, but passive devices such as electric capacity and inductance have been used, the simple structure of circuit, the circuit cost is reduced, simultaneously because need not provide stable operating voltage for above-mentioned passive device, consequently when carrying out metal foreign matter detection, the influence that receives the induced voltage that produces on the foreign matter detection coil has been reduced, metal foreign matter's detection device's stability and reliability have been promoted, thereby can in time discover the metal foreign matter that exists on the power transmitting antenna of transmitting terminal, the potential safety hazard has been got rid of.

Example six:

the embodiment of the application also provides a method for detecting the metal foreign matter, which is used for detecting the metal foreign matter of the power transmitting antenna and is specifically described below with reference to the accompanying drawings.

Referring to fig. 14, it is a flowchart of a method for detecting a metal foreign object according to a sixth embodiment of the present application.

The detection method is performed by using a detection device, and the structure and the working principle of the detection device can be referred to the description in the above embodiments, which is not described herein again, and the method includes the following steps:

s1301: an electrical parameter of the first resonant circuit or the second resonant circuit is detected.

When metal foreign matters exist on the power transmitting antenna, the inductance of the foreign matter detection coil of the second resonant circuit is changed due to the eddy current effect of the metal foreign matters, so that the electric parameters of the first resonant circuit and the second resonant circuit are changed. Therefore, whether metal foreign matters exist on the current power transmitting antenna can be judged by detecting the electric parameters of the first resonant circuit or the second resonant circuit and comparing the electric parameters with the reference value.

S1302: and comparing the detected electric parameter with a reference value, and determining that the metal foreign matter exists when the absolute value of the difference value between the electric parameter and the reference value exceeds a preset range.

In one possible implementation, the current flowing through the first resonant circuit may be detected, and the current may be compared with a current reference value to determine whether a metal foreign object is present on the current power transmitting antenna.

In another possible implementation manner, the voltage across the second resonant circuit may be detected, and the voltage may be compared with a voltage reference value to determine whether a metal foreign object exists on the current power transmitting antenna.

In yet another possible implementation, the reactance of the second resonant circuit may be obtained by detecting a voltage across the second resonant circuit and a current flowing through the second resonant circuit, and comparing the reactance value with a reactance reference value to determine whether a metallic foreign object is present on the present power transmitting antenna.

It can be understood that the method for detecting the metal foreign matter can be used for detecting the metal foreign matter not only by using the power transmitting antenna at the transmitting end, but also in other metal detection fields, such as security metal detection, and the like, and the application is not limited to this.

By utilizing the detection method of the metal foreign matters, the metal foreign matters existing on the power transmitting antenna of the transmitting terminal can be found in time, and potential safety hazards are eliminated.

It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.

The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. The detection device of the metal foreign matter is characterized by being applied to the detection of the metal foreign matter on a power transmitting antenna; the method comprises the following steps: the detection circuit comprises a first resonance circuit, a second resonance circuit, a detection circuit and a foreign matter detection controller;

the input end of the first resonant circuit is connected with a constant voltage source, and the output end of the first resonant circuit is connected with the second resonant circuit;

the first resonant circuit is used for converting the constant voltage source into a current source;

the first resonance circuit at least comprises a series resonance circuit formed by a first inductor and a first capacitor, and the second resonance circuit at least comprises a parallel resonance circuit formed by a foreign object detection coil and a second capacitor; the resonant frequency of the first resonant circuit coincides with the resonant frequency of the second resonant circuit;

the detection circuit is used for detecting the electric parameter of the first resonance circuit or the second resonance circuit;

2. The detecting device according to claim 1, wherein a first terminal of the first inductor is connected to a first terminal of the constant voltage source, a second terminal of the first inductor is connected to a first terminal of the first capacitor, and a second terminal of the first capacitor is connected to a second terminal of the constant voltage source;

the second resonant circuit is connected in parallel between the first end of the first capacitor and the second end of the first capacitor.

3. The sensing device of claim 1, wherein the first resonant circuit further comprises: a third capacitor;

the first end of the first inductor is connected with the first end of the constant voltage source, the second end of the first inductor is connected with the first end of the third capacitor, the first end of the third capacitor is connected with the first end of the first capacitor, and the second end of the first capacitor is connected with the second end of the constant voltage source;

4. The detecting device according to claim 2 or 3, wherein the foreign object detecting coil and a second capacitor are connected in parallel and then connected between a first end of the first capacitor and a second end of the first capacitor.

5. A testing device according to claim 2 or 3 wherein the second resonant circuit further comprises: a fourth capacitor;

the foreign matter detection coil is connected with the fourth capacitor in series and then connected with the second capacitor in parallel, and the foreign matter detection coil is connected between the first end of the first capacitor and the second end of the first capacitor after being connected in parallel.

6. A testing device according to any of claims 1-3 wherein the testing circuit comprises a first current sensor;

the first current sensor for detecting a current flowing through the first resonance circuit;

the foreign object detection controller is specifically configured to compare the detected current flowing through the first resonant circuit with a current reference value, and determine that a metal foreign object exists when an absolute value of a difference between the detected current flowing through the first resonant circuit and the current reference value exceeds a preset current range.

7. A testing device according to any of claims 1-3 wherein the testing circuit comprises a voltage sensor;

the voltage sensor is used for detecting the voltage at two ends of the second resonant circuit;

the foreign matter detection controller is specifically configured to compare the detected voltage at the two ends of the second resonant circuit with a voltage reference value, and determine that a metal foreign matter exists when an absolute value of a difference between the voltage at the two ends of the second resonant circuit and the voltage reference value exceeds a preset voltage range.

8. The sensing device of any one of claims 1-3, wherein the sensing circuit includes a voltage sensor and a second current sensor;

the second current sensor for detecting a current flowing through the second resonance circuit;

the foreign object detection controller is used for obtaining the reactance of the second resonance circuit according to the voltage at two ends of the second resonance circuit and the current flowing through the second resonance circuit; and comparing the reactance of the second resonance circuit with a reactance reference value, and determining that the metal foreign matter exists when the absolute value of the difference value between the reactance of the second resonance circuit and the reactance reference value exceeds a preset reactance range.

9. A transmitting end, comprising: a detecting device for metallic foreign matter according to any one of claims 1 to 8; further comprising: a power transmitting antenna;

the power transmitting antenna is used for transmitting the alternating magnetic field;

the detection device of the metal foreign matter is used for detecting whether the metal foreign matter exists on the power transmitting antenna.

10. The transmitting end according to claim 9, further comprising: a transmitting end controller;

the transmitting terminal controller is used for receiving the foreign matter detection result sent by the foreign matter detection controller; and the foreign matter detection controller is also used for sending a foreign matter detection starting instruction and a foreign matter detection stopping instruction to the foreign matter detection controller.

11. A wireless charging system, comprising: the transmitting end of any of claims 9-10, further comprising a receiving end;

the transmitting end is used for transmitting alternating current in the form of an alternating magnetic field;

and the receiving end is used for receiving the alternating current in the form of the alternating magnetic field transmitted by the transmitting end and providing the alternating current to the power utilization terminal.

12. A detection method of metal foreign matter is characterized in that the method is applied to metal foreign matter detection of a power transmitting antenna; the detection method is carried out by using a detection device, and the detection device at least comprises the following steps: a first resonant circuit, a second resonant circuit; the input end of the first resonant circuit is connected with a constant voltage source, and the output end of the first resonant circuit is connected with the second resonant circuit; the first resonant circuit is used for converting the constant voltage source into a current source, and the voltage of the constant voltage source is the product of the total reactance of the first resonant circuit and the second resonant circuit and the current of the current source; the first resonance circuit at least comprises a series resonance circuit formed by a first inductor and a first capacitor, and the second resonance circuit at least comprises a parallel resonance circuit formed by a foreign object detection coil and a second capacitor; the resonant frequency of the first resonant circuit coincides with the resonant frequency of the second resonant circuit; the foreign body detection coil is close to the power transmitting antenna;

the method comprises the following steps:

detecting an electrical parameter of the first resonant circuit or the second resonant circuit;